A. Field of the Invention
The invention relates to medical treatment devices and, more particularly, to devices for supplying medication or other materials to localized sites within the vascular system.
B. Prior Art
The diagnosis and treatment of defects in the vascular system presents a major challenge to the medical profession. The most effective methods for diagnosis and treatment of vascular disorders requires access to the vascular tree. Typically, this is accomplished by puncture of the vascular wall. Not only is this difficult in patients with diseases such as atherosclerosis, but complications such as bleeding and thromboembolisms increase the risk of such procedures. Thromboses are significant contributors to limb loss or deaths due to vascular failure, and yet themselves are frequent byproducts of vascular treatment.
Venous access is typically provided by means of catheters which puncture the vein. Access by this method has typically been short-term and limited to peripheral venous access because of complications such as thrombophlebitis. In-dwelling cathethers have been particularly susceptible to clot formation. In recent years, longer term central venous access has been provided by devices such as the Hickman catheter and the subcutaneous infusion port. These devices have markedly improved venous access, but have not been useful for arterial access because of such factors as substantially higher arterial pressure, among others. Indeed, the use of cathethers in artieries is recognized as especially dangerous.